OF THE ALIMENTARY TRACT 231 



(Lynch, 1922A and 1022B), the writer reported upon 

 culture experimentation with the organism and 

 named two new species, B. gemmagina and B. sporo- 

 gina, the former differing from B. hominis Brumpt 

 in exhibiting peripheral budding in culture, and the 

 latter in showing by the same method a process 

 taken to be endosporulation. Since that time much 

 incidental note has been taken of Blastocystis, par- 

 ticularly since it commonly grows profusely in a 

 number of the culture mediums used for growing 

 protozoa, often to the detriment of the purpose of 

 the cultures. 



Blastocystis is a very common body to be seen in 

 the examination of feces. In the ordinary stool it is 

 usually not numerous, is about 5 to 15 microns in 

 diameter, usually rounded, but may be ovoid or more 

 elongated. It has a delicate capsule, allowing al- 

 teration in shape. There is a sharp differentiation 

 into peripheral and central zones, the former usually 

 of uniform width in the rounded organisms and 

 deeper at the poles of the ovoid or elongated than it 

 is around the middle. This peripheral zone is trans- 

 parent and colorless at times, at others greenish and 

 refractive. In it occurs the nucleus or nuclei, ap- 

 pearing as highly refractive bodies. 



The central body is rounded or ovoid, depending 

 on the shape of the organism, and may be greenish 

 and refractive, when the peripheral zone is trans- 

 parent, or transparent, when the periphery is refrac- 

 tive. Not infrequently the division of the cell into 



